1. Field of the Invention
The invention relates to a method for making a thin-film magnetic head having different materials depending on the zones of the film. It also relates to a write/read head made according to this method.
2. Description of the Prior Art
With prior art methods, when making thin films which may be about 2 to 5 micrometers thick, it is not possible to obtain, in one and the same film, zones of a determined composition next to zones of a different composition, with distinct boundaries between the zones. According to the invention, a structure of this type, where certain zones have harder materials, forms a structure offering greater resistance to surface wear.
This structure can be applied preferably to a write/read magnetic head.
Integrated magnetic heads are presently produced as read or write elements for hard disks. In this context of their use, the magnetic heads fly above the surface of the disk. Their flying height is about 0.3 micrometers and, while they are being used, they never rub against the disk except when this disk is being started or stopped.
By contrast, in video tape recorder type devices, the writing medium is a magnetic tape made of either oxide or metal, and the heads are in contact with the tape. The result of this is a rate of wear which, according to present standards for VHS heads, is about 20 micrometers per 2000 hours of functioning, thus establishing the lifetime of the video tape recorder.
For thin-film heads, the problem of the interface between the tape and the write/read head is more crucial because it involves dimensions in the range of a few micrometers for the active magnetic parts. For the thin-film deposits have thicknesses of about 5 micrometers, and the gap is 0.2 micrometers, the substrate on which the films are deposited being about 500 micrometers thick.
Hence, there are reasons for taking precautions against the premature wearing out of these magnetic heads.
The magnetic thin films presently in the market are made by the cathodic sputtering of materials such as Fe and Ni, or mixtures such as FeSiAl. The structure that results from cathodic sputtering is a polycrystalline and locally non-homogeneous structure.
By contrast, the making of constituent elements of this type entails using, according to the invention, a known technique for epitaxial depositing by laser heating as described in the article: "Laser Selective Depositing of GaAs on Si" by S. M. Bedair et al in the journal Applied Physics Letter, No. 48(2), Jan. 13th 1986.
The technological flexibility of the method of the invention makes it possible to envisage structures with adjacent or stacked deposits, suited to the use for which the magnetic head is designed.